热处理对SIMP钢的显微组织和力学性能的影响

Effect of heat treatment on microstructure and mechanical properties of SIMP steel

SIMP钢是先进核嬗变系统（ADS系统）散裂靶用候选结构材料,优化热处理工艺可以提高其力学性能。本文研究了正火温度和回火温度对SIMP钢组织与力学性能的影响,结果表明：当正火温度从980℃提高至1050℃时,原奥氏体晶粒尺寸和板条束的宽度增大,材料的冲击性能降低,但蠕变性能却大幅提高;当回火温度从760℃降至700℃时,马氏体板条的回复程度降低,析出相更加弥散,蠕变性大幅提升,但韧脆转变温却明显上升。

SIMP steel has been developed as a new structural material for the spallation target in accelerator driven sub-critical system（ADS）. The present study aimed at improving mechanical properties of the steel by optimizing heat treatment process. Microstructure of the SIMP steel after different heat treatments was characterized,and the corresponding mechanical properties were measured. The results show that increasing normalizing temperature from 980 ℃ to 1050 ℃ results in a coarse martensitic block size,which improves the creep property but leads to a remarkable drop in the impact absorbed energy. Decreasing the tempering temperature from 760 ℃ to 700 ℃ leads to a smaller lath size and finer dispersed precipitates,which brings high creep strength but an increased ductile brittle transition temperature（ DBTT）.